Radiation Therapy for Prostate Cancer

Topic Contents

Treatment Overview

Radiation therapy uses high doses of radiation, such as X-rays, to destroy cancer cells. The radiation damages the genetic material of the cells so that they can't grow. Although radiation damages normal cells as well as cancer cells, the normal cells can repair themselves and function, while the cancer cells cannot.

Radiation therapy may be used alone or combined with hormonal treatment to treat prostate cancer. It is most effective in treating cancers that have not spread outside the prostate. But it also may be used if the cancer has spread to nearby tissue. Radiation is sometimes used after surgery to destroy any remaining cancer cells and to relieve pain from metastatic cancer.

Radiation is delivered in one of two ways.

External-beam radiation therapy uses a large machine to aim a beam of radiation at your tumor. After the area of cancer is identified, an ink tattoo no bigger than a pencil tip is placed on your skin so that the radiation beam can be aimed at the same spot for each treatment. This helps focus the beam on your cancer to protect nearby healthy tissue from the radiation. External radiation treatments usually are done 5 days a week for 4 to 9 weeks. But sometimes higher doses of radiation can be given over several weeks (hypofractionated radiation therapy). If cancer has spread to your bones, shorter periods of treatment may be given to specific areas to relieve pain.

Conformal radiotherapy (3D-CRT) uses a three-dimensional planning system to target a strong dose of radiation to the prostate cancer. This helps to protect healthy tissue from radiation.

Proton beam therapy uses a different type of energy (protons) rather than X-rays. This allows a higher amount of specifically-directed radiation, which protects nearby healthy tissues (especially the rectum). Sometimes proton therapy is combined with X-ray therapy. It is available only at big medical centers.

Brachytherapy, or internal radiation therapy, uses dozens of tiny seeds that contain radioactive material. It may be used to treat early-stage prostate cancer. Needles are used to insert the seeds through your skin into your prostate. The surgeon uses ultrasound to locate your prostate and guide the needles.

High-dose-rate (HDR) brachytherapy uses radioactive material placed into the prostate for a very brief period of time (seconds to minutes) before being removed. The radiation is delivered this way several times.

Low-dose-rate (LDR) brachytherapy uses a lower dose of radioactive material that is left in place permanently.

Sometimes treatment combines brachytherapy with low-dose external radiation. In other cases, treatment combines surgery with external radiation or hormone therapy may be used along with brachytherapy.

Before radiation therapy is scheduled, your doctor probably will order a bone scan and CT scan to find out whether the cancer has spread to other parts of your body. If it has, your doctor may offer you the option of a clinical trial for treatment.

Radiation treatments to the prostate can injure the rectum, which is behind the prostate. Your doctor may suggest using a hydrogel spacer. It's a water-based gel. Before you have radiation treatments, the gel is injected into the space between the prostate and rectum. The gel quickly becomes solid, and it stays solid for about 3 months. After that, it dissolves. The spacer shields the rectum from much of the radiation aimed at the prostate.

What To Expect

Side effects may last only as long as the treatment, or they may continue and become chronic. Some side effects occur after treatment, such as erection problems. For some men, this problem gets gradually worse over the course of several years after treatment.

When radiation therapy is given as the primary treatment for men who have prostate cancer that has not grown outside the prostate (localized prostate cancer), side effects may include:

Skin changes from external beam radiation therapy. This includes the skin looking like it is sunburned where the radiation was targeted.

Feeling very tired (fatigue) or not having much of an appetite.

Urinary problems, such as having a burning feeling when you urinate, needing to urinate often or urgently, or passing blood in your urine.

Erection problems that develop over time, often several years after radiation.

The side effects may be different for radiation used after surgery for prostate cancer or for cancer that has spread to other parts of the body (metastatic prostate cancer).

Talk with someone on your treatment team if you want a complete list of side effects. And when you notice any side effects, be sure to report them to your treatment team. They may have ideas that will help you feel better.

Radiation treatments to the prostate can injure the rectum, which is behind the prostate. Your doctor may suggest using a hydrogel spacer. It's a water-based gel. Before you have radiation treatments, the gel is injected into the space between the prostate and rectum. The gel quickly becomes solid, and it stays solid for about 3 months. After that, it dissolves. The spacer shields the rectum from much of the radiation aimed at the prostate.

Why It Is Done

Radiation therapy is used for:

Cancer that has not spread in men over 70.

Cancer that has spread to the bones, is not getting better with hormonal treatment, and is causing pain.

Cancer that has come back in the prostate after surgery.

Cancer cells that may remain after surgery, especially if all the cancer cannot be removed.

How Well It Works

For men with localized prostate cancer, radiation works about as well as surgery (radical prostatectomy). With either treatment, the chance of the cancer spreading is low. One study looked at men who had localized prostate cancer and found that the risk of dying was very low and about the same, no matter what option men chose.footnote 1

For treating advanced prostate cancer that has grown beyond the prostate but not into lymph nodes or bones, external-beam radiation combined with hormone therapy can work better than surgery. This treatment often results in controlling cancer growth and in many years of disease-free survival.footnote 2

Radiation therapy also works well to treat pain when prostate cancer has spread to the bone.footnote 3

Risks

Radiation treatment for prostate cancer may increase a man's risk for having another cancer later in life, such as bladder or rectal cancer.

For men with higher-risk prostate cancer, radiation treatment is given along with hormone therapy. Hormone therapy has side effects, such as the loss of bone density and muscle mass. It can also increase the risk for bone fractures, diabetes, and heart disease.

What To Think About

The goal of radiation therapy is to deliver the highest dose possible to the prostate while protecting the rest of the nearby organs (such as the bladder and rectum) from unnecessary radiation. Newer ways of giving radiation, such as 3D-CRT, IMRT, and proton beam therapy, are more accurate. This has helped to reduce problems caused by radiation.

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